Regulation of germination by targeted mutagenesis of grain dormancy genes in barley

Abstract

Summary High humidity during harvest season often causes pre‐harvest sprouting in barley (Hordeum vulgare). Prolonged grain dormancy prevents pre‐harvest sprouting; however, extended dormancy can interfere with malt production and uniform germination upon sowing. In this study, we used Cas9‐induced targeted mutagenesis to create single and double mutants in QTL FOR SEED DORMANCY 1 (Qsd1) and Qsd2 in the same genetic background. We performed germination assays in independent qsd1 and qsd2 single mutants, as well as in two double mutants, which revealed a strong repression of germination in the mutants. These results demonstrated that normal early grain germination requires both Qsd1 and Qsd2 function. However, germination of qsd1 was promoted by treatment with 3% hydrogen peroxide, supporting the notion that the mutants exhibit delayed germination. Likewise, exposure to cold temperatures largely alleviated the block of germination in the single and double mutants. Notably, qsd1 mutants partially suppress the long dormancy phenotype of qsd2, while qsd2 mutant grains failed to germinate in the light, but not in the dark. Consistent with the delay in germination, abscisic acid accumulated in all mutants relative to the wild type, but abscisic acid levels cannot maintain long‐term dormancy and only delay germination. Elucidation of mutant allele interactions, such as those shown in this study, are important for fine‐tuning traits that will lead to the design of grain dormancy through combinations of mutant alleles. Thus, these mutants will provide the necessary germplasm to study grain dormancy and germination in barley.

Characteristics of the Seed Germination and Seedlings of Six Grape Varieties (V. vinifera)

“…Beak-cutting treatments improved the germination rate, potential, and index of the six tested varieties, but also improved the emergence and seedling rates, consistent with the results of previous studies [21,39]. Increasing the seedling rate can conserve resources [40]. The emergence and seedling rates of Ecolly and Cabernet Sauvignon were increased by pre-germination in a bean sprouter, but these rates were decreased for Garanior, Dunkelfelder, and Marselan.…”

A crucial role for a node‐localized transporter, HvSPDT, in loading phosphorus into barley grains

“…The gRNAtargeted regions of regenerated plants were amplified and sequenced to check mutations in the HvSPDT gene by PCR using the specific primers listed in Table S1. The DNA extraction and PCR procedures were as described in Hisano et al (2022) and Hisano & Sato (2016), respectively. Two independent lines with 1 bp insertion and 1 bp deletion (designated as hvspdt-1 and hvspdt-2, induced by gRNA4 and gRNA6, respectively) were selected and used for phenotypic analysis as described in the section 'Phenotypic analysis of hvspdt mutants', 'Labeling experiments with radioisotope 32 P' and 'P mobility experiment' below (Fig.…”

Transcriptome analysis of knockout mutants of rice seed dormancy gene OsVP1 and Sdr4

“…Strong seed dormancy causes a decline in the germination rate, which will lead to a decline in the number of effective crop individuals, thus resulting in decreased yield (Shuai et al 2016). But the weak dormancy leads to pre-harvest sprouting (PHS) in some temperate areas where the crop harvesting season meets high humidity (Hisano et al 2022). In southern China, PHS damages about 6% of the acreage of conventional rice and as much as 20% of hybrid rice acreage due to the long-term rainy weather during harvest season (Doebley et al 2006).…”

“…In southern China, PHS damages about 6% of the acreage of conventional rice and as much as 20% of hybrid rice acreage due to the long-term rainy weather during harvest season (Doebley et al 2006). The balance between dormancy and germination is one of the main goals driving rice breeding program (Hisano et al 2022).…”